As radio base stations for use in mobile communications, there are a large base station which provides a relatively-wide service area, and a small base station which provides a relatively-narrow service area. Generally, a large base station has a relatively-wide capacity, which is represented by the number of channels accommodated therein and so on, whereas a small base station has a relatively-small capacity.
For example, in W-CDMA (wide-band code-division multiple access) mobile communications, as a large base station, there is a base station having 2,000 or more channels for sound rates, and as a small base station, there is a base station having about 100 channels.
Mobile communications of cellular type represented by W-CDMA mobile communications provide a relatively-wide service area using a large base station and a small base station as mentioned above. On the other hand, mobile communications of cordless type represented by PHS (Personal Handyphone System) mobile communications (including mobile communications intended for home use) provide a relatively-narrow service area.
Thus, conventionally, mobile communications of cellular type have not been used for a relatively-narrow service area, especially for a home-use service area. However, in recent years, a micro base station which provides a very-narrow service area, such as a home-use service area, has been examined.
However, taking a narrow restricted transmission environment for home use and a small number of users in a private home into consideration, it is not realistic for an individual to install such a micro base station into his or her home and to use it because it is difficult to downsize it and make it fall drop in price because of its having unnecessary functions which comply with transmission environments and a superfluous capacity of accommodating many users. The same goes for a case in which such a micro base station is installed into an elevator or the like.
As a prior art technology, there has been provided a mobile communications system which carries out a different process for a base station according to the type of the base station (refer to patent references 1 to 3). However, because the prior art mobile communications system does not carry out a different process according to the scale of the base station, it is also difficult to downsize it and make it fall drop in price.    [Patent reference 1] JP,10-276475,A    [Patent reference 2] JP,11-055175,A    [Patent reference 3] JP,05-344051,A